ATMOSPHERIC ELECTRICITY:  DEMONSTRATIONS OF FUNDAMENTALS OF STATIC ELECTRICITY USING A VAN DE GRAF GENERATOR:

The standard Van de Graf generator can be used to illustrate:

• Dielectric breakdown in air (move spheres closer or apart)
• Shielding of electric fields by conducting cylinder (use cylinder with pith ball sensors (lower right))
• Induced charging - like charges repel and opposites attract (use wand with foil or small sphere on tether)
• Mechanism of charging by contact separation (discuss VandeGraf mechanics)
• Electrostatic forces (use small sphere on thether)
• Charge leakage enhanced by taping a tack to the free standing sphere.

Voltages up to about 400KV.  Low current device is reasonably safe - EXCEPT FOR ANY FORM OF COMPUTER, VLSI ELECTRONICS, MEDICAL ELECTRONICS AND THE LIKE!!  KEEP ALL THESE ITEMS AT A SAFE DISTANCE.

Contact separation listing:

Contact between any two materials causes charge to separate as shown.  Example:  Aluminum and polyethelene -> Aluminum goes positive and polyethylene goes negative.

+ mica, wool, nylon, glass, silk, aluminum, cotton, wood, plexiglass, was, PVC, polystyrene, polyethylene, rubber, teflon, saranwrap  -

©2000.  John Hart, University of Colorado